Hydraulic Speed Ratio Control Method for Vehicles with a Ball Variator Continuously Variable Transmission

Abstract

This invention relates to controlling the speed ratio of a Continuous Variable Transmission with a hydraulic method. The Ball Planetary CVT design is adapted with a mechanical and hydraulic addition. The carrier of the ball-type variator is supported by hydraulic actuators. The result is that the speed ratio is controlled by both a set speed ratio and the torque flowing through the CVT. Subsequently, torque peaks are avoided and controllability of the CVT is increased.

1 - 29 . (canceled) 
     
     
         30 . A method of controlling a CVP ratio of a continuously variable planetary transmission having a plurality of tiltable balls coupled to a first carrier member and a second carrier member, the first carrier member adapted to rotate with respect to the second carrier member, the method comprising:
 providing a hydraulic actuator operably coupled to at least one carrier member, the hydraulic actuator comprising a first electronic valve configured to control the relative position of the second carrier member with respect to the first carrier member;   receiving a plurality of signals indicative of a first carrier position, a second carrier position, a first pressure in hydraulic communication with the first electronic valve, a CVP input speed, and a CVP output speed;   commanding the first electronic valve to operate at a fluid supply pressure;   monitoring a CVP ratio based on the CVP input speed and the CVP output speed; and   changing in the first carrier position with respect to the second carrier position of the CVP based at least in part on the ratio of the CVP.   
     
     
         31 . The method of  claim 30 , wherein the fluid supply pressure is based at least in part on a desired damping of the CVP. 
     
     
         32 . The method of  claim 31 , wherein the desired damping of the CVP is based at least in part on a torque input to the CVP. 
     
     
         33 . The method of  claim 30 , wherein the fluid supply pressure is determined using a calibration table of commanded hydraulic pressure based at least in part on the torque input to the CVP. 
     
     
         34 . A method of controlling a CVP ratio of a continuously variable planetary transmission having a plurality of tiltable balls coupled to a first carrier member and a second carrier member, the first carrier member adapted to rotate with respect to the second carrier member, the method comprising:
 providing a hydraulic actuator operably coupled to the second carrier member, the hydraulic actuator comprising a first electronic valve and a second electronic valve configured to control the relative position of the second carrier member with respect to the first carrier member;   receiving a plurality of signals indicative of a first carrier position, a second carrier position, a first pressure in hydraulic communication with the first electronic valve, a second pressure in hydraulic communication with the second electronic valve, a CVP input speed, and a CVP output speed;   commanding the first electronic valve to operate at a first pressure;   commanding the second electronic valve to operate at a second pressure;   monitoring a CVP ratio based on the CVP input speed and the CVP output speed; and   changing the first carrier position with respect to the second carrier position of the CVP based at least in part on the ratio of the CVP.   
     
     
         35 . The method of  claim 34 , wherein the CVP ratio is determined based at least in part on the CVP output speed. 
     
     
         36 . The method of  claim 34 , wherein the first carrier position with respect to the second carrier position is indicative of the CVP ratio. 
     
     
         37 . The method of  claim 34 , wherein the first and/or second electronic valves are electronic proportional valves.